1. Field of the Invention
The present invention relates to an electromagnetic flowmeter for measuring the flow rate of a fluid in a pipe and, more particularly, to full pipe detection in an electromagnetic flowmeter.
2. Description of the Related Art
Electromagnetic flowmeters utilize the principle of electrodynamic induction for flow rate measurement of a fluid medium. In an electromagnetic flowmeter, a magnetic field is generated across a measuring section of the flowmeter pipe through which the medium flows, which by operation of Faraday's law, generates a voltage orthogonal to both the flow of the medium and the magnetic field. The induced voltage is measured by a pair of electrodes on opposite sides of the measuring section. This induced voltage is proportional to the flow velocity of the medium to be measured and averaged over the cross section of the pipe.
Considerable measurement errors can occur if the measuring pipe is not filled completely but only partially with the medium to be measured, because the measuring apparatus bases the resultant measurements on a completely filled measuring pipe. In addition to incompleteness of the measuring pipe, factors such as gas bubbles in the medium, corrosion of electrodes, liner damage, electrode fouling, among others, also lead to measurement errors.